Method of fabricating semiconductor device and fabrication system of semiconductor device

ABSTRACT

A method of fabricating a semiconductor device and a fabrication system of the semiconductor device are provided. The method includes sequentially forming a film to be etched and a dielectric film and measuring a thickness of the dielectric film, forming a photoresist film on the dielectric film, performing a lithography process using the measured thickness of the dielectric film to form a photoresist film pattern, and etching the dielectric film and the film to be etched using the photoresist film pattern.

BACKGROUND OF THE INVENTION

The present invention relates to a method of fabricating a semiconductordevice and a fabrication system of the semiconductor device, and morespecifically, to a method of fabricating a semiconductor device, inwhich critical dimension control of a to-be-etched film pattern can beachieved in a reliable manner, and a fabrication system of thesemiconductor device.

Generally, a semiconductor fabricating process includes variousprocesses, including deposition, lithography, etching, ion implantation,and so on. The lithography for forming a desired film pattern to beetched, which includes forming a photoresist film pattern and etchingusing the photoresist film pattern, is a key process in thesemiconductor fabrication.

However, in the event of non-uniformity in the thickness of a dielectricfilm formed on the film to be etched, even if a photoresist patternhaving a desired critical dimension is formed in a lithography process,a critical dimension of the to-be-etched film pattern formed in thesubsequent etching process may not be efficiently controlled. Forexample, if a thickness of the dielectric film formed on the film to beetched is greater than a desired thickness, the critical dimension ofthe to-be-etched film pattern is reduced to be smaller than a desiredcritical dimension. On the contrary, if a thickness of the dielectricfilm formed is smaller than the desired thickness, the criticaldimension of the to-be-etched film pattern is increased to be greaterthan the desired critical dimension.

SUMMARY OF THE INVENTION

The present invention provides a method of fabricating a semiconductordevice having improved reliability.

The present invention also provides a fabrication system of asemiconductor device having improved reliability.

The above and other objects of the present invention will be describedin or be apparent from the following description of the variousembodiments.

According to an aspect of the present invention, a method of fabricatinga semiconductor device and a fabrication system of the semiconductordevice are provided. The method includes sequentially forming a film tobe etched and a dielectric film and measuring a thickness of thedielectric film, forming a photoresist film on the dielectric film,performing a lithography process using the measured thickness of thedielectric film to form a photoresist film pattern, and etching thedielectric film and the film to be etched using the photoresist filmpattern.

According to another aspect of the present invention, there is provideda method of fabricating a semiconductor device including sequentiallyforming a film to be etched and a dielectric film and measuring athickness of the dielectric film, forming a photoresist film on thedielectric film, performing a lithography process using the measuredthickness of the dielectric film to form a photoresist film pattern, andetching the dielectric film and the film to be etched using thephotoresist film pattern, wherein when the dielectric film has a firstthickness, the photoresist pattern has a first critical dimension, andwhen the dielectric film has a second thickness, the photoresist patternhas a second critical dimension.

According to still another aspect of the present invention, there isprovided a fabrication system of a semiconductor device including a filmforming system of forming a film to be etched, a dielectric film and aphotoresist film on a substrate, a thickness metrology system ofmeasuring thicknesses of the dielectric film, a lithography system ofperforming a lithography process using the photoresist film, a controlsystem of controlling processing parameters of the lithography systemusing data on the measured thicknesses of the dielectric film, and anetching system of etching the dielectric film and the film to be etchedusing the photoresist film pattern.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow diagram of a method of fabricating a semiconductordevice according to an embodiment of the present invention;

FIGS. 2 through 5 illustrate intermediate structures in the method offabricating a semiconductor device according to an embodiment of thepresent invention;

FIG. 6 illustrates a relationship between a thickness of a dielectricfilm and a critical dimension of a to-be-etched film pattern when thecritical dimension of a photoresist film pattern is the sameirrespective of the thickness of the dielectric film;

FIG. 7 illustrates a relationship between a thickness of a dielectricfilm and a critical dimension of a to-be-etched film pattern when thecritical dimension of a photoresist film pattern changes according tothe thickness of the dielectric film;

FIG. 8 illustrates a variation in the critical dimension of aphotoresist film pattern according to the thickness of the dielectricfilm in the method of fabricating a semiconductor device according to anembodiment of the present invention; and

FIG. 9 illustrates a fabrication system of a semiconductor deviceaccording to another embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Advantages and features of the present invention and methods ofaccomplishing the same may be understood more readily by reference tothe following detailed description of preferred embodiments and theaccompanying drawings. The present invention may, however, be embodiedin many different forms and should not be construed as being limited tothe embodiments set forth herein. Rather, these embodiments are providedso that this disclosure will be thorough and complete and will fullyconvey the concept of the invention to those skilled in the art, and thepresent invention will only be defined by the appended claims. In someembodiments, structures of devices and techniques which are well knownin the art will not be discussed in detail herein so as not tounnecessarily obscure aspects of the present invention.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, components, and/orsections, these elements, components, and/or sections should not belimited by these terms. These terms are only used to distinguish oneelement, component or section from another element, component, orsection. Thus, a first element, component, or section discussed belowcould be termed a second element, component, or section withoutdeparting from the teachings of the present invention.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of exampleembodiments. As used herein, the singular forms “a”, “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises”, “comprising,”, “includes” and/or “including”, when usedherein, specify the presence of stated features, integers, steps,operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components, and/or groups thereof.

Spatially relative terms, e.g., “below,” “beneath,” “lower,” “above,”“upper” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would be oriented “above” the other elements orfeatures. Thus, the exemplary term “below” may encompass both anorientation of above and below. The device may be otherwise oriented(rotated 90 degrees or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly.

FIG. 1 is a flow diagram of a method of fabricating a semiconductordevice according to an embodiment of the present invention, and FIGS. 2through 5 illustrate intermediate structures in the method offabricating a semiconductor device according to an embodiment of thepresent invention.

Referring to FIGS. 1 and 2, a film 20 to be etched, which is referred toas a to-be-etched film hereinafter, and a dielectric film 30 aresequentially formed on a substrate 10 (S10).

The substrate 10 may be a Si substrate, a SOI (Silicon On Insulator)substrate, a GaAs substrate, a SiGe substrate, a ceramic substrate, aquartz substrate, or a glass substrate for display. Alternatively, thesubstrate 10 may, for example, be a P-type substrate. In addition,although not shown, the substrate 10 may be used in a form of a P-typeepitaxial layer grown on the substrate 10.

Although not shown in the drawings, transistors, interlayer insulatingfilms, contact holes, metal interconnections, and so on, may be formedon the substrate 10, the selection of which can be readily envisioned bya person of ordinary skill in the art, and the description thereaboutwill not be given.

The to-be-etched film 20 is a film that is to be etched in apredetermined pattern in a continuous etching process, and examples ofthe to-be-etched film 20 include an oxide film, a nitride film, adielectric film, such as a low-k film or a high-k film, a conductivefilm, such as a polysilicon film, and so on. Meanwhile, although notshown, an etch stop layer having a high etch selectivity with respect tothe to-be-etched film 20 may be formed under the to-be-etched film 20.

The dielectric film 30, which is formed on the to-be-etched film 20, maybe used to prevent reflection of light in a lithography process or maybe used as a mask layer in an etching process. The dielectric film 30may be a single film or a multi-layered film having a high etchingselectivity with respect to a photoresist film and capable ofeffectively preventing reflection of light in a lithography process. Forexample, when the to-be-etched film 20 is an anti-reflective coating(ARC), the dielectric film 30 may be an interlayer dielectric (ILD)film.

Next, a thickness D of the dielectric film 30 is measured using athickness measuring device (S20). Here, the thickness D of thedielectric film 30 may be measured at a predetermined position, e.g., atleast one position, of the substrate 10.

Referring to FIGS. 1, 3 and 4, a photoresist film 40 is formed on thedielectric film 30 (S30), and a photoresist film pattern 45 having acritical dimension (CD) CDp is formed using a lithography process (S40).Here, the CDp may be the smallest width of a line or the smallestdistance between two lines specified by a design rule for amanufacturing process of a particular element. For convenience ofexplanation, the CDp is shown as the smallest width of a line specifiedby a design rule, but the CDp may not be limited thereto.

Particularly, in the method of fabricating the semiconductor deviceaccording to an exemplary embodiment of the present invention, thelithography process may be performed using the thickness D of thedielectric film 30 measured prior to the lithography process. In detail,the lithography process may be performed while varying processingparameters, such as a projecting focus depth FD, exposure energy and/orexposure time, using the thickness D of the dielectric film 30 measuredprior to the lithography process.

For example, as shown in FIG. 3, in the lithography process including alight source 140, a condenser lens 130, a mask pattern 120, and aprojection lens 110, the focus depth FD can be determined by thethickness D of the dielectric film 30. Here, the focus depth FD maycorrespond to positions on an optimum focal plane of an optical systemwith respect to a reference plane, for example, a top surface or centerof the photoresist film 40, which are measured along an optical axis,that is, an axis perpendicular to the optimum focal plane.

When the thickness D of the dielectric film 30 becomes greater than adesired thickness, the focus depth FD may be reduced during alithography projection process. On the other hand, when the thickness Dof the dielectric film 30 becomes smaller than the desired thickness,the focus depth FD may be increased during the lithography projectionprocess.

Accordingly, even if there is a change in the thickness of thedielectric film 30 due to a processing error, an error in thelithography process due to a focus deviation may be practically avoided,thereby enhancing the reliability of the lithography process. In otherwords, the critical dimension CDp of the photoresist film pattern 45formed in the lithography process may be effectively controlled by apredetermined critical dimension CDp determined by a specified designrule, not by a lithography process error. Further, the criticaldimension of the to-be-etched film pattern formed in the subsequentetching process may also be effectively controlled by a specific designrule.

Further, in the method of fabricating the semiconductor device accordingto an exemplary embodiment of the present invention, the exposure energyand/or exposure time may also be determined using the thickness of thedielectric film 30 measured prior to the lithography process. That is tosay, the exposure energy and/or exposure time of the lithography processmay be determined using the thickness of the dielectric film 30 measuredprior to the lithography process, and the critical dimension CDp of thephotoresist film pattern 45 may be determined. In detail, when thethickness D of the dielectric film 30 is greater than a desiredthickness, the exposure energy and/or exposure time of the lithographyprocess are increased, and the critical dimension CDp of the photoresistfilm pattern 45 may be increased. On the other hand, when the thicknessD of the dielectric film 30 is smaller than the desired thickness, theexposure energy and/or exposure time of the lithography process may bereduced and the critical dimension CDp of the photoresist film pattern45 may be decreased. Accordingly, even if there is a change in thethickness of the dielectric film 30 due to a processing error, thecritical dimension of the to-be-etched film pattern can be effectivelycontrolled in the subsequent etching process, thereby fabricating asemiconductor device having improved reliability, which will later bedescribed in detail with reference to FIGS. 6 through 8.

Referring to FIGS. 1 and 5, the dielectric film 30 and the to-be-etchedfilm 20 are etched using the photoresist film pattern 45 to form adielectric film pattern 35 and a to-be-etched film pattern 25 (S50). Thedielectric film pattern 35 has an etching selectivity different fromthat of the dielectric film 30 or the to-be-etched film 20. Thus, thedielectric film pattern 35 may have a predetermined tilt angle θ, unlikethe to-be-etched film pattern 25. Here, the predetermined tilt angle θof the dielectric film pattern 35 may be an angle of inclination formedbetween a sidewall of the dielectric film pattern 35 and the bottom wallof the dielectric film pattern 35, and may be set to a predeterminedvalue according to a material forming the dielectric film 30 and anetching material used in the etching process. In addition, theto-be-etched film pattern 25 resulting from the etching process of theto-be-etched film 20 may have a predetermined critical dimension CDe.Particularly, in the method of fabricating the semiconductor deviceaccording to an exemplary embodiment of the present invention, even ifthere is a change in the thickness of the dielectric film 30 (or thedielectric film pattern) due to a processing error, the to-be-etchedfilm pattern 25 may have substantially the same critical dimension CDe,irrespective of the thickness of the dielectric film 30, which willlater be described in detail with reference to FIGS. 6 through 8.

FIG. 6 illustrates a relationship between a thickness of a dielectricfilm and a critical dimension of a to-be-etched film pattern when thecritical dimension of a photoresist film pattern is the sameirrespective of the thickness of the dielectric film, FIG. 7 illustratesa relationship between a thickness of a dielectric film and a criticaldimension of a to-be-etched film pattern when the critical dimension ofa photoresist film pattern varies the same according to the thickness ofthe dielectric film, and FIG. 8 illustrates a variation in the criticaldimension of a photoresist film pattern according to the thickness ofthe dielectric film in the method of fabricating a semiconductor deviceaccording to an embodiment of the present invention.

Referring to FIG. 6, when the to-be-etched film and the dielectric filmthat are sequentially formed, are etched using a photoresist filmpattern 41 having substantially the same critical dimension CDpirrespective of the thickness of the dielectric film (or the thicknessof a dielectric film pattern), first and second critical dimensions CDe1and CDe2 of first and second to-be-etched film patterns 21 a and 21 bmay vary according to first and second thicknesses D1 and D2 of thedielectric film and tilt angles θ of first and second dielectric filmpatterns 31 a and 31 b. When the dielectric film has the first thicknessD1, the first to-be-etched film pattern 21 a may have the first criticaldimension CDe1. When the dielectric film has the second thickness D2,the second to-be-etched film pattern 21 b may have the second criticaldimension CDe2.

For example, when the dielectric film having the first thickness D1 andthe to-be-etched film are etched using the photoresist film pattern 41having the critical dimension CDp, the to-be-etched film pattern 21 amay have the first critical dimension CDe1, which is about “arctanθ×D1”smaller than the critical dimension CDp of the photoresist film pattern41. In contrast, when the dielectric film having the second thickness D2and the to-be-etched film are etched using the photoresist film pattern41 having the critical dimension CDp, the to-be-etched film pattern 21 bmay have the second critical dimension CDe2, which is about “arctanθ×D2”smaller than the critical dimension CDp of the photoresist film pattern41. In other words, the photoresist film pattern 41 is formed using thephotoresist film pattern 41 having the same critical dimension CDpirrespective of the thickness of the dielectric film. Accordingly, whenthe thickness of the dielectric film is greater than a desired thicknessdue to a processing error, a critical dimension (e.g., CDe2) of ato-be-etched film pattern (e.g., 21 b) may become smaller than thedesired critical dimension (e.g., CDe1). On the other hand, when thethickness of the dielectric film is smaller than the desired thicknessdue to a processing error, a critical dimension of a to-be-etched filmpattern may become greater than the desired critical dimension.

However, in the method of fabricating the semiconductor device accordingto an exemplary embodiment of the present invention, as shown in FIG. 7,first and second critical dimensions CDp1 and CDp2 of first and secondphotoresist film patterns 42 a and 42 b may be determined by thethickness of the dielectric film. Accordingly, the foregoing problemsmay be substantially addressed. In detail, when a first dielectric film32 a has a first thickness D1, a first photoresist film pattern 42 ahaving a first critical dimension CDp1 may be formed by adjustingprocessing parameters, such as exposure energy and/or exposure time, ina lithography process, and an etching process may be performed using thefirst photoresist film pattern 42 a. On the other hand, when a seconddielectric film 32 b has a second thickness D2, a second photoresistfilm pattern 42 b having a second critical dimension CDp2 may be formedby adjusting processing parameters, such as exposure energy and/orexposure time, in a lithography process, and an etching process may beperformed using the second photoresist film pattern 42 b. Here, adifference between the first and second critical dimensions CDp1 andCDp2 of the first and second photoresist film patterns 42 a and 42 b maybe determined by a difference between the first and second thicknessesD1 and D2 of the first and second dielectric films 32 a and 32 b andarctan values of each tilt angle θ of the first and second dielectricfilms 32 a and 32 b.

While the processing parameters of the lithography process, such as aprojecting focus depth, exposure energy and/or exposure time, etc.,described in the illustrated embodiment, are determined according to thethickness of the dielectric film measured prior to the lithographyprocess, the present invention is not limited by the illustratedprocessing parameters. In another exemplary embodiment, only theexposure energy and/or exposure time may be determined according to thethickness D of the dielectric film 30 measured prior to the lithographyprocess.

FIG. 9 illustrates a fabrication system of a semiconductor deviceaccording to another embodiment of the present invention.

Referring to FIG. 9, the fabrication system of a semiconductor deviceaccording to another embodiment of the present invention includes a filmformation system 100, a thickness metrology system 110, a lithographysystem 120, a control system 130 and an etching system 140.

The film formation system 100 includes devices for forming a film to beetched, a dielectric film, a photoresist film, etc. on a substrate. Forexample, the film formation system 100 may include a deposition devicefor depositing a film on the substrate, using PVD (Physical VaporDeposition), CVD (Chemical Vapor Deposition), ALD (Atomic LayerDeposition), or the like. The film formation system 100 may also includea coating device for forming a coating of, for example, silicon, anorganic material, or photoresist, on the substrate. However, the presentinvention is not limited to the illustrated devices, and the filmformation system 100 may include various devices for forming variouskinds of films on the substrate.

The thickness metrology system 110 includes a thickness measuring devicefor measuring thicknesses of the dielectric film formed on thesubstrate. In an exemplary embodiment, the thickness metrology system110 may include an optical imaging device for measuring thicknesses of adielectric film. The thicknesses of the dielectric film can be measuredat a predetermined position on the substrate. The thickness metrologysystem 110 may be formed as an independent system, or may beincorporated into the film formation system 100 or the lithographysystem 120.

The lithography system 120 includes an exposure device for exposing asubstrate having a photoresist film formed using a photoresist filmpattern through a mask pattern, and a development device for developingthe exposed substrate. For example, the exposure device may include anyone of known reduction projection exposure devices (e.g., a stepper).Here, the mask pattern may be projected onto the photoresist film in areduced size. In particular, the processing parameters of thelithography system 120, such as a projecting focus depth FD, exposureenergy and/or exposure time, etc., may be controlled by the controlsystem 130. Following the exposure, the exposed substrate may betransferred to the development device. Here, the exposed substrate maybe subjected to a post exposure bake process, or a chemical process forremoving an exposed (or unexposed) region of the photoresist film.

The illustrated systems and methods may be realized in hardware,software, firmware, a particular processor, or various combinationsthereof. In the illustrated example, the foregoing embodiments may beimplemented by one or more program storage devices and may be performedin software that is an application executable by a predetermined deviceor instrument including an appropriate architecture. Since various stepsof the illustrated system modules and methods may be performed desirablyin software, the relationship between system components (or flows ofprocessing steps) may vary according to the way in which the applicationis programmed.

While the present invention has been particularly shown and describedwith reference to exemplary embodiments thereof, it will be understoodby those of ordinary skill in the art that various changes in form anddetails may be made therein without departing from the spirit and scopeof the present invention as defined by the following claims. It istherefore desired that the present embodiments be considered in allrespects as illustrative and not restrictive, reference being made tothe appended claims rather than the foregoing description to indicatethe scope of the invention.

1. A method of fabricating a semiconductor device comprising:sequentially forming a film to be etched and a dielectric film andmeasuring a thickness of the dielectric film; forming a photoresist filmon the dielectric film; performing a lithography process using themeasured thickness of the dielectric film to form a photoresist filmpattern; and etching the dielectric film and the film to be etched usingthe photoresist film pattern.
 2. The method of claim 1, wherein theforming of the photoresist film pattern comprises adjusting exposureenergy and/or exposure time in the lithography process based on themeasured thickness of the dielectric film.
 3. The method of claim 2,wherein the forming of the photoresist film pattern comprises adjustingthe focus depth in the lithography process based on the measuredthickness of the dielectric film.
 4. The method of claim 1, wherein acritical dimension of the photoresist film pattern increases as thethickness of the dielectric film becomes increased.
 5. The method ofclaim 1, wherein the dielectric film is an anti-reflective film.
 6. Themethod of claim 1, wherein the photoresist film is formed aftermeasuring the thickness of the dielectric film.
 7. A method of method offabricating a semiconductor device comprising: sequentially forming afilm to be etched and a dielectric film and measuring a thickness of thedielectric film; forming a photoresist film on the dielectric film;performing a lithography process using the measured thickness of thedielectric film to form a photoresist film pattern; and etching thedielectric film and the film to be etched using the photoresist filmpattern, wherein When the dielectric film has a first thickness, thephotoresist pattern has a first critical dimension, and when thedielectric film has a second thickness, the photoresist pattern has asecond critical dimension.
 8. The method of claim 7, wherein a lateralsurface of the dielectric film pattern is tilted at a predetermined tiltangle with respect to a bottom surface of the dielectric film pattern,and a difference between the first and second critical dimensions of thephotoresist film pattern is determined by a difference between the firstand second thicknesses of the dielectric film and an arctan value of thetilt angle.
 9. A fabrication system of a semiconductor devicecomprising: a film forming system of forming a film to be etched, adielectric film and a photoresist film on a substrate; a thicknessmetrology system of measuring thicknesses of the dielectric film; alithography system of firming a photoresist film pattern process usingthe photoresist film; a control system of controlling processingparameters of the lithography system using data on the measuredthicknesses of the dielectric film; and an etching system of etching thedielectric film and the film to be etched using the photoresist filmpattern.
 10. The fabrication system of claim 9, wherein a criticaldimension of the photoresist film is determined by the data on themeasured thicknesses of the dielectric film.